In article <[EMAIL PROTECTED]>, michael <[EMAIL PROTECTED]> wrote: >However, for one simple test (v.low memory, v.low comms, high compute) >case which is Fortran90 compiled using mpich, I actually found turning >HT off helped -- when it was on then for -np 2 there was no speed up >(top implied they ran on same physical processor). I presume this was >because the CPU was fully busy anyhow so the 2nd thread had to wait (you >seem to imply the opposite but I don't follow why!).
Turning on the "SMT scheduler support" in the kernel is supposed to prevent exactly this. If two jobs are runnable, they will be run on 2 different CPUs (if you have them), not on 1 CPU with 2 threads. Mike. -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
